It depends on the actual type of data - take a 2Tb oracle db that is mostly empty you will be getting a 90%+ compression ratio - so your LTO-2 cartridge will show the capacity used as 2000Gb. The typical ratio IBM used to qoute was 3-1 in recent years they changed this to 2-1, hence the 200-400 figure. The algorithm used for the comression is a modified ZL algorithm - similar to the algorithm used for pkzip etc. If you send already compressed data your tape usage will show 200Gig or less - if you were getting negative compression ratios - data already compressed can grow if comressed again. So - there is no clear-cut answer - work on the native capacity(200G), and everything else you get is a bonus.
Cheers Christo ----- Original Message ----- From: "Chandrashekar, C. R. (Chandrasekhar)" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, April 16, 2004 7:50 AM Subject: Re: LTO tape cartridge(200GB/400GB) stores data 500GB+. > This is not a puzzle for me, Actually I want to know how much data it can > compress, Is there any one using same tape library. Which helps to estimate > the total storage capacity. > > Just to know how much percentage of compression in 3583L23 library using > 3580ULTGen2 drive. > > Thanks, > c.r.chandrasekhar > > -----Original Message----- > From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] Behalf Of > Christo Heuer > Sent: Friday, April 16, 2004 10:51 AM > To: [EMAIL PROTECTED] > Subject: Re: LTO tape cartridge(200GB/400GB) stores data 500GB+. > > > Hi, > > I see you are a Tivoli certified consultant (TSM) - maybe they missed that > part in > the certification exam - why don't you read up on compression - if this > puzzles you > I'm sure plenty other things will confuse the hell out of you. > > Christo > ----- Original Message ----- > From: "Chandrashekar, C. R. (Chandrasekhar)" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Friday, April 16, 2004 6:51 AM > Subject: LTO tape cartridge(200GB/400GB) stores data 500GB+. > > > > Hi, > > > > Just for clarification, I'm using LTO-Ult tape cartridge having capacity > of > > 200GB/400GB, Tape library 3582L23 with two 3580-LTOG2 drives with firmware > > 38D0, and devclass was defined with device-type=LTO and Format=ULTRIM2C. > Now > > the tape is storing more then 500GB of data, Is it normal behavior. > > > > Thanks, > > CRC, > > > > C.R.Chandrasekhar. > > Systems Analyst. > > Tivoli Certified Consultant (TSM). > > TIMKEN Engineering & Research - INDIA (P) Ltd., Bangalore. > > Phone No: 91-80-51362222. > > Email:[EMAIL PROTECTED] > > > > > > > > > > ********************************************************************** > > PLEASE NOTE: The above email address has recently changed from a previous > naming standard -- if this does not match your records, please update them > to use this new name in future email addressed to this individual. > > > > This message and any attachments are intended for the > > individual or entity named above. If you are not the intended > > recipient, please do not forward, copy, print, use or disclose this > > communication to others; also please notify the sender by > > replying to this message, and then delete it from your system. > > > > The Timken Company > > ********************************************************************** > > ______________________________________________ > E-mail Disclaimer and Company Information > > http://www.absa.co.za/ABSA/EMail_Disclaimer > > > ********************************************************************** > PLEASE NOTE: The above email address has recently changed from a previous naming standard -- if this does not match your records, please update them to use this new name in future email addressed to this individual. > > This message and any attachments are intended for the > individual or entity named above. If you are not the intended > recipient, please do not forward, copy, print, use or disclose this > communication to others; also please notify the sender by > replying to this message, and then delete it from your system. > > The Timken Company > ********************************************************************** ______________________________________________ E-mail Disclaimer and Company Information http://www.absa.co.za/ABSA/EMail_Disclaimer
